title: Cryo-electron microscopy reveals the membrane insertion mechanism of V. cholerae hemolysin.
abstract: Vibrio cholerae hemolysin (HlyA) is a 65 kDa pore-forming toxin which causes lysis of target eukaryotic cells by forming heptameric channels in the plasma membrane. Deletion of the 15 kDa C-terminus β-prism carbohydrate-binding domain generates a 50 kDa truncated variant (HlyA50) with 1000-fold-reduced pore-forming activity. Previously, we showed by cryo-electron microscopy that the two toxin oligomers have central channels, but the 65 kDa toxin oligomer is a seven-fold symmetric structure with bowl-, ring-, and arm-like domains, whereas the 50 kDa oligomer is an asymmetric jar-like heptamer. In the present study, we determined three-dimensional(3D) structures of HlyA and HlyA50 in presence of erythrocyte stroma and observed that interaction of the 65 kDa toxin with the stroma induced a significant decrease in the height of the β-barrel oligomer with a change in conformation of the ring- and arm-like domains of HlyA. These features were absent in interaction of HlyA50 with stroma. We propose that this conformational transition is critical for membrane-insertion of the toxin.
authors.affiliation: a Division of Electron Microscopy , National Institute of Cholera and Enteric Diseases , P-33, C.I.T. Road, Scheme-XM, Beleghata, Kolkata , 700010 , India .
authors.forename: Somnath
authors.initials: S
authors.lastname: Dutta
authors.forename: Kalyan K
authors.initials: KK
authors.lastname: Banerjee
authors.forename: Amar N
authors.initials: AN
authors.lastname: Ghosh
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry* / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism*; D020285:Cryoelectron Microscopy; D006460:Hemolysin Proteins / Q000737:chemistry* / Q000378:metabolism; D008958:Models, Molecular; D011487:Protein Conformation; D014734:Vibrio cholerae / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D006460:Hemolysin Proteins; C084287:hlyA protein, Vibrio cholerae
keywords: Vibrio cholerae hemolysin; cryo-electron microscopy; pore-forming toxin; single particle analysis